Teleradiology Overview Systems and Applications - Sanjoy Sanyal
 

Teleradiology Overview Systems and Applications - Sanjoy Sanyal

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Dr Sanjoy Sanyal, then Associate Professor, presented this at a seminar on 27 July2007 in Seychelles medical college. It talks about the technology behind Teleradiology (Bandwidth, Network, Image ...

Dr Sanjoy Sanyal, then Associate Professor, presented this at a seminar on 27 July2007 in Seychelles medical college. It talks about the technology behind Teleradiology (Bandwidth, Network, Image Resolution, DICOM, PACS etc), the Healthcare Applications, Telemammography, and limitations.
Educational value of this material is multi-dimensional involving Information Technology, Healthcare, Administration, Medical Professionals, Radiologists, Medical Informaticians, Technology Marketing Specialists

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Teleradiology Overview Systems and Applications - Sanjoy Sanyal Teleradiology Overview Systems and Applications - Sanjoy Sanyal Presentation Transcript

  • Teleradiology – overview, systems and applications
    • Dr Sanjoy Sanyal
    • MBBS, MS, MSc (UK), ADPHA, ADHRD
    • Seychelles
    Staff seminar on 27 July 2007 in Seychelles medical college
  • TABLE OF CONTENTS
    • Definition / types of teleradiology
    • Components
    • Configurations
    • Equipment specifications
    • DICOM
    • PACS
    • Applications
    • Telemammography
    • Costs
    • References
  • 1. DEFINITION Teleradiology: A means of electronically transmitting patient’s radiographic images and consultative text from one location to another
  • 1. TYPES OF TELEMEDICINE
  • 2. COMPONENTS – Telemedicine system in general
  • 2. COMPONENTS – Basic teleradiology system
    • Image sending station
    • Transmission network
    • Receiving/image review station
  • A. Image Sending Station
    • Image (film) digitizer
    • Network interface device (e.g. phone modem)
  • Image (film) digitizer
    • Direct digitization : No need for X-ray film and processing equipment (best)
    • TV camera digitizers (‘low-end’)
    • CCD scanner digitizers (‘mid-level’)
    • Laser scanner digitizers (‘high-end’)
      • Last three digitizers perform same function: Input X-ray film -> into scanner; analog image of film -> digital image.
  • Camera digitizer
  • Network interface device
    • Film digitizer has converted the image to digital format
    • Data is sent to the modem upon command of the equipment operator
      • Modem converts digital data into electrical impulses that are sent along transmission network.
  • B. Transmission Network
    • Wire
    • Fiberoptics
    • Microwave
      • Provided by telephone companies. This network utilizes both wire and fiberoptics
      • Transmission speed (and cost) closely related to transmission mode.
  • C. Receiving / Image Reviewing Station
    • 1. Network interface (modem)
    • 2. PC with storage medium (e.g. disc drive)
    • 3. One or two TV monitors
    • 4. Optional hard copy device printer
  • Receiving/Image Review Station
  • 3. CONNECTION CONFIGURATIONS
    • Point-to-point connection
    • Local Area Network (LAN)
    • Wide Area Network (WAN)
  • A. Point-to-point connection
    • The basic sending and review station directly connected by a dedicated transmission network (e.g. a single wire or fiberoptic cable)
  • A. Point-to-point connection
  • A. Point-to-point connection
  • B. Local Area Network (LAN)
    • Dedicated transmission network
    • Multiple sending / review stations attached
    • Images can be sent from several different locations within a building (or cluster of buildings) to a review station
  • B. Local Area Network (LAN)
  • C. Wide Area Network (WAN)
    • Many LANs interconnected - ‘super’ network
    • Connected by routers
    • Interconnected LANs represented as ‘ network cloud ’
  • C. Wide Area Network (WAN)
  • C. WAN – Telephone network
    • Telephone network services can be thought of as a WAN
    • Widely used transmission network
    • Advantages of using the telephone network
      • (1) It already exists
      • (2) Inner workings / complexities of network are transparent to end users
      • (3) Allows for readily available long / short distance connections
      • (4) Costs are low
  • Server-mediated communication
  • Server-mediated communication
  • 4. EQUIPMENT SPECIFICATIONS
    • A. Sending Station Specifications
      • Image resolution
      • Image compression
      • Transmission speed
  • Image resolution
    • Pixel : 512 x 512 (w x h), 1024 x 1024, or 2048 or 2048
    • Grey scale (density) number : 256 (8-bit depth) to 4096 (12 bit-depth)
    • File size:
      • 512 x 512 x 8 bit-depth = 2,097,152 bits
      • 1024 x 1024 x 12 bit-depth = 12,582,912 bits (6 times larger file size)
  • Image resolution – pixels 240 dpi 120 dpi 60 dpi 30 dpi
  • Image resolution – grey scale 255 grey levels / pixel 15 grey levels / pixel 5 grey levels / pixel 2 grey levels / pixel
  • Image compression
    • Compression algorithms: DCT
      • Lossy: JPEG (common)
      • Lossless: Huffman JPG; JPG-LS; RLE
    • Compression ratios: 2:1 to > 15:1
      • < 3:1 is lossless
      • > 3:1 is lossy
  • Image compression
  • Image compression
  • Image compression
  • Transmission
    • DS 0 (64 Kbps)
    • ISDN (128 Kbps)
    • T 1 (1.544 Mbps)
    • ATM: Asynchronous Transfer Mode
  • Transmission speed
    • Balance resolution, compression, and transmission speed parameters
  • Transmission speed
  • 4. EQUIPMENT SPECIFICATIONS
    • B. Receiving/Image Review Station specifications
      • Modem : receiving unit modem must be > maximum speed of sending station
      • Computer hardware
      • Image enhancement software
      • TV monitor : Resolution, size, split-screen, brightness
  • Image enhancement software
    • Grey scale window/level
    • Magnification image enhancement
    • Colour, grey-scale mapping
    • Positive-negative reversal
    • Annotation
    • Minification
    • Edge enhancement
    • Image flip/rotate
    • Cine and histogram equalization
  • TV monitor
    • Resolution : 512 x 512 pixels to 2048 x 2048 pixels
    • Size : 14 – 21 inches
    • Split-screen : Display 2 or more different images at the same time
    • Brightness :
      • High footlamberts (greater brightness) better
      • Brightness differential between shades is greater
      • Easier for the human eye to detect
  • Digital display monitors
    • Digital display monitors : For decoding digital images for producing diagnostic quality images for reporting
    • Quality concerns : Whether they can match image resolution of X-ray film
      • Pixel content: Lack of resolution is not because of the pixel content; typically 2K pixels x 2K lines
      • Level of contrast : The problem is with the level of contrast - usually <100 shades of grayscale
  • Digital display monitors
    • Special techniques for correcting deficiency:
      • Histogram-based image transformation
      • Filter-based image transformation
      • Unsharp mask
    • These techniques give radiologist the ability to use ‘window’ and ‘level’ control (sort of contrast and brightness adjustments) to get adequate contrast distinction for confident reporting
  • Contrast-brightness control
  • Digital display monitor
  • 5. DICOM
    • DICOM : Digital imaging & communication
    • ACR / NEMA standard: A set of rules
    • Medical scanners (US, CT, MRI, X-ray) store and exchange images in DICOM format.
  • 5. DICOM
    • Allows exchange of images between digital imaging machines, computers and hospitals.
    • Allows teleradiology to expand from a vendor-dependent proprietary protocols and hardware to an open Internet-like system
  • DICOM images
  • DICOM viewer
  • 6. PACS
    • PACS: Picture Archiving and Communication System
    • For distribution , storage and management of digital images and patient information.
    • Aiming towards filmless hospital
    • Web-based PACS (AMICAS ® Inc): D iagnostic-quality radiology image management services; secure image capture, distribution, workflow integration and image archiving.
  • PACS network
  • 7. APPLICATIONS
    • Radiologists on call
    • Hospital physicians
    • Primary care / rural physicians
    • Tertiary subspecialty consultations
    • Computer-aided diagnosis (CAD)
  • A. Radiologists on call
    • On-call radiologist uses portable telerad receiving station at home
    • Patient images transmitted from radiology dept to radiologist’s home for immediate review
  • B. Hospital physicians
    • ICU patient images taken in Radiology Department
    • Quickly transmitted to ICU for review by the team responsible for that patient's care
    • Other involved physicians can also view images
  • C. Primary care / rural physicians
    • Primary physician can send images taken in the clinic to a radiologist in a distant location for reading and consultation
  • C. Primary / rural physicians
  • D. Tertiary super-specialist radiology consultations
    • A community hospital radiologist can send a complete set of images to a tertiary super-specialist (i.e. paediatric radiologist)
  • E. Computer-aided diagnosis
    • Processing / analyzing digital medical images on workstation allows computer assistance to physician for interpretation
    • Drawback : Increases number of negative / unnecessary biopsies without increasing incidence of positive diagnosis in mammography
  • E. Computer-aided diagnosis
  • E. Computer-aided diagnosis
  • 7. TELEMAMMOGRAPHY
    • More women in remote areas
    • Mammography experts are in cities
    • Mammograms require special expertise
    • Mammogram films are 35-55 MB/film
    WHY?
  • 7. TELEMAMMOGRAPHY
    • High resolution is must for minute lesions
    • So cannot compress images
    • So need high-speed transmission lines
    • Satellite and T1 is the answer
    • NASA is the satellite and telemedicine expert
  • 7. TELEMAMMOGRAPHY
    • STN: Satellite Telemammography Network
    • Ka-Band satellites: Advanced Communication Technology Satellite (ACTS)
    • Earth stations: T1 VSAT (Very Small Aperture Terminal)
      • #1: Cleveland Clinic, OH
      • #2: NASA Glenn Research Center @Lewis Field – ASCL
      • #3: University of Virginia, Charlottesville
  • Satellite network
  • NASA satellite
  • Earth station – NASA Glenn
  • Earth station – University
  • Radiology - reading films
  • 9. COSTS
    • Low end equipment: $15,000 to $20,000
    • High performance systems: > $100,000
    • High quality sending station: ~ $35,000 to $40,000
    • Dual CRT receiving / viewing station: $45,000 to $55,000
    • ( Figures are as of 1 st half of this decade )
  • 10. REFERENCES
    • University of Iowa: http://www.radiology.uiowa.edu/MoreRAD/Teleradiology/Tele.html
    • Stephen Kinnear: http://www.scit.wlv.ac.uk/~c9581158/graphic/graphic.html
    • Sreedhar Raja: http://www.websamba.com/dicom4india
    • Chris Rorden: http://www.psychology.nottingham.ac.uk/staff/cr1/dicom.html#contrast
  • 10. REFERENCES
    • NHS Purchasing and Supply Agency, UK http:// www.pasa.doh.gov.uk/dme/radiology/pacs.stm
    • Osman Ratib: http://www.hon.ch/Library/papers/ratib.html
    • NASA Glen Research Center: http://web.archive.org/web/20051002003701/ctd.lerc.nasa.gov/5610/mammography/SLSandE.html
    • http://www.nasa.gov/centers/glenn/news/pressrel/97_telem.html
  • 10. REFERENCES
    • NASA Glen Research Center: http://www.grc.nasa.gov/WWW/RT1995/5000/5660k2.htm
    • SNAB: http://ctd.grc.nasa.gov/organization/branches/snab/telemedicine.html
    • http://www.medicalimagingmag.com/issues/articles/2006-12_07.asp
    • Wootton and Craig. Introduction to Telemedicine. 1999.
  •